In two-for-one twister textile yarn processing machines, each spindle assembly for processing of yarn includes a rotatable rotor mechanism defining a generally vertically and axially extending passageway therethrough for receiving moving yarn for processing, a stationary yarn carrier mounted coaxially around the rotor mechanism and having a generally vertically and axially extending passageway therethrough communicating with the yarn passageway through the rotor mechanism, and at least one supply package of yarn carried by the carrier mechanism. Yarn is withdrawn from the supply package and is passed through the yarn passageways in the carrier mechanism and the rotor mechanism for twisting of the yarn in a well-known manner.
It is often desirable to regulate the tension on the yarn, particularly highly twisted yarn, passing from the supply package to the yarn passageways by a yarn brake mechanism to insure uniformity in the yarn processing. For this purpose, yarn brake rings have been utilized, such as shown in German Pat. No. 563,593, wherein the yarn brake ring, also known as a float ring, is slipped onto a yarn intake tube forming a part of the yarn carrier and cooperates with a generally cylindrical braking surface on such intake tube to receive the yarn between the ring and the braking surface to apply tension to the moving yarn. As the yarn passes between the braking ring and the braking surface, the braking ring is lifted by movement of the yarn and floats up and down the intake tube to apply a frictional braking force to the yarn and thus tension the yarn.
In some yarn processing operations, particularly two-for-one twisting, two or more yarns are often processed or twisted together. In this type of operation, separate cross-wound supply packages of yarn are provided wherein the yarns are simultaneously withdrawn from the supply packages and processed or twisted together. When withdrawing at least two yarns from the separate supply packages, the yarns are usually under different tensions due to nonuniform sizes of the separate supply packages, the nature of cross-winding the separate supply packages, etc.
Accordingly, if a yarn brake ring, of the type known from the above discussed German Pat. No. 563,593 is utilized for tensioning two or more yarns from separate cross-wound supply packages, uniform tension will not be applied to each of the yarns inasmuch as the floating brake ring will move or float upwardly under the influence of one of the yarns to create a gap between it and the braking surface where the other yarn is passing therebetween. This is particularly actue with highly twisted sewing yarns wherein kinks may occur in one of the yarns which is not being uniformly tensioned with other of the yarns, resulting in problems in yarn processing.
Accordingly it is the object of this invention to provide a yarn brake mechanism and process for applying substantially uniform tension to at least two yarns moving from separate cross-wound supply packages of yarn in a textile yarn processing machine, particularly a two-for-one twister textile yarn processing machine.
It has been found by this invention that this object may be accomplished by providing such a yarn brake mechanism and process comprising generally the following.
A member is mounted in the machine and positioned in the linear path of movement of the yarns from the supply packages and defines an outer frusto-conical shaped, yarn braking surface tapered in the linear direction of movement of the yarns. A comb-like, braking, ring member is slidably positioned around the braking surface and dimensioned for receiving the moving yarns in braking engagement between the braking surface and the ring member. The ring member has slightly spaced-apart teeth of pliantly elastic, springy material positioned therearound and extending therefrom generally in the linear direction of movement of the yarns. The teeth are inclined with respect to the ring both inwardly into contact with the braking surface and circumferentially in the circumferential direction of the movement of the yarns as they are unwound from the yarn packages, so that at least two of the teeth overlap each other along each directrix of the braking surface. Means are provided for limiting the sliding movement of the braking ring member along the braking surface in the linear direction of movement of the yarns.
Each of the yarns is frictionally engaged by the ring member and braking surface and by at least two or more of the teeth extending from the ring member regardless of the position of the individual yarns or the position of the ring member on the braking surface, so that each of the yarns are substantially uniformly tensioned regardless of the individual tension on the yarns as they are withdrawn from the separate supply packages.
Although comb-like, braking, ring members have been used for yarn tensioning in knitting, hosiery or other fabric producing machines, such ring members have not been utilized in yarn processing machines, particularly two-for-one twisters, for substantially uniformly tensioning two or more yarns being withdrawn from separate cross-wound yarn supply packages for processing in a textile yarn processing machine, particularly a two-for-one twister. For example, German Patent Publication Nos. AS 1 262 847, OS 24 27 766 and AS 24 17 552, as well as the magazine entitled "textil praxis International" of August 1976 at page 863 and a brochure published by AB IRO of Sweden, disclose brake rings of the type having bristles or teeth extending therefrom and inclined inwardly thereof for cooperating with a generally cylindrical braking surface for applying tension to a single yarn only from a reserve or storing mechanism feeding the yarn to knitting and hosiery machines.